1. Field of the Invention
The present invention relates to a piezoelectric film and a piezoelectric device, and more particularly to a piezoelectric film and a piezoelectric device having high piezoelectric performance.
2. Description of the Related Art
There has been known a piezoelectric device that is obtained by combining a piezoelectric film having a piezoelectric property of producing displacement due to application of a drive voltage, with electrodes through which the drive voltage is applied to the piezoelectric film. A piezoelectric film is a thin film, which is beneficial for achieving greater fineness and is therefore extremely useful, but does not have good piezoelectric performance and is therefore problematic in that it cannot yield sufficient device performance.
Known piezoelectric materials are PZT (lead zirconate titanate), or substituted PZT in which a portion of the A or B site of the PZT is substituted with another element. It is known that PZT that is doped with donor ions having higher valence than the valence of the substituted ions has improved piezoelectric performance compared to pure PZT.
For example, Japanese Patent Application Publication No. 2009-221037 discloses a piezoelectric film in which the B site atoms are substituted with Ta or Nb in a range of 5% to 20%, and SiO2 or GeO2 is included as an additive.